From owner-freebsd-questions@FreeBSD.ORG  Thu Apr  9 21:27:35 2015
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id D8667AFC
 for <freebsd-questions@freebsd.org>; Thu,  9 Apr 2015 21:27:35 +0000 (UTC)
Received: from wonkity.com (wonkity.com [67.158.26.137])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "wonkity.com", Issuer "wonkity.com" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id 88FE1DCA
 for <freebsd-questions@freebsd.org>; Thu,  9 Apr 2015 21:27:35 +0000 (UTC)
Received: from wonkity.com (localhost [127.0.0.1])
 by wonkity.com (8.14.9/8.14.9) with ESMTP id t39LRQO2032630
 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO);
 Thu, 9 Apr 2015 15:27:26 -0600 (MDT)
 (envelope-from wblock@wonkity.com)
Received: from localhost (wblock@localhost)
 by wonkity.com (8.14.9/8.14.9/Submit) with ESMTP id t39LRQaF032627;
 Thu, 9 Apr 2015 15:27:26 -0600 (MDT)
 (envelope-from wblock@wonkity.com)
Date: Thu, 9 Apr 2015 15:27:26 -0600 (MDT)
From: Warren Block <wblock@wonkity.com>
To: mfv <mfv@bway.net>
Subject: Re: Setting Trim _AFTER_ a New Install
In-Reply-To: <20150409152321.65de5fd0@gecko4>
Message-ID: <alpine.BSF.2.20.1504091521170.1276@wonkity.com>
References: <20150409152321.65de5fd0@gecko4>
User-Agent: Alpine 2.20 (BSF 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII; format=flowed
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3
 (wonkity.com [127.0.0.1]); Thu, 09 Apr 2015 15:27:27 -0600 (MDT)
Cc: freebsd-questions@freebsd.org
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions/>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 09 Apr 2015 21:27:35 -0000

On Thu, 9 Apr 2015, mfv wrote:

> Hello,
>
> I've recently installed FreeBSD r10.1 using bsdinstall and then loaded
> a large number of programs and data.  After spending considerable time
> on the installation I discovered that my SSD has TRIM which appears
> to be quite useful. After some investigation I understand that it is a
> simple flag that can be set after booting into single user mode.
>
> I hope my questions are  simple:
>
> If TRIM is enabled will it mess up the disk so that everything has to be
> reinstalled?

No, it will not harm the data.  That said, before running tunefs to 
enable it, make a backup.  Always make a backup.

> If not, is there anything else I should be aware of?

If you used ZFS-on-root, tunefs(8) and TRIM do not apply.  ZFS uses TRIM 
natively now, but I'm not sure if that was in 10.1 or only now in 
10-STABLE.